AU2021200923A1

AU2021200923A1 - Picket post

Info

Publication number: AU2021200923A1
Application number: AU2021200923A
Authority: AU
Inventors: David Neil Brims
Original assignee: Vtex Pty Ltd
Current assignee: Vtex Pty Ltd
Priority date: 2020-02-13
Filing date: 2021-02-12
Publication date: 2021-09-02

Abstract

A picket post comprising: an elongate web extending between two ends of the post; a pair of flanges extending along the length of the post with the elongate web being transversely positioned between said flanges; wherein each of said flanges at one end of the post terminates to form a respective convergent ground engaging structure to allow said one end of the post to be driven into the ground. C' a, RZ*

Description

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PICKET POST TECHNICAL FIELD

[001] The present invention relates to post, particularly a picket post. The picket post

may be employed in applications such as fencing, demarcation, signage etc.

BACKGROUND

[002] Any references to methods, apparatus or documents of the prior art are not to

be taken as constituting any evidence or admission that they formed, or form part of

the common general knowledge.

[003] Posts for use in applications such as fencing, demarcation, signage etc are

known. Such posts are usually formed from steel. Steel fence posts have been known

for many years that are roll-formed to have a Y-shad oor T-shaped profile. Typically

such posts are provides with a pointed end to facilitate the post being driven into the

earth more easily during installation. Fence posts, especially those for use in e.g. rural

applications, require a combination of strength (to enable the post to be driven into the

earth) and ductility (so the post can deform without breaking when pressure is applied

to it by e.g. livestock). It is also desirable for the posts to withstand high temperatures

particularly during periods of bushfires to ensure that fencing is not permanently

destroyed during such fires.

[004] Pickets posts such as star pickets are usually provided with a series of spaced

holes in one or more flanges of the star picket to enable strands of fencing wire to be

secured to the post, usually by tying each wire strand to the post with a separate short length of wire tie threaded through an individual hole, or by employing a wire clips.

However, the holes and/or passages formed in the posts have typically been a weak

point of the post, in-use. In this regard, when excessive forces are applied to the post

(e.g. by livestock) that results in a bending moment in the post, the post has been

known to fracture at these holes and passages. When the post fractures, usually at

the hole or passage closest to the ground, the post can no longer be used and must

be replaced.

[005] It is therefore desirable to provide an improved picket post which addresses

some of the issues with the prior art.

SUMMARY OF INVENTION

[006] In an aspect, the invention provides a picket post comprising: an elongate web

extending between two ends of the post; a pair of flanges extending along the length

of the post with the elongate web being transversely positioned between said flanges;

wherein each of said flanges at one end of the post terminates to form a respective

convergent ground engaging structure to allow said one end of the post to be driven

into the ground.

[007] In an embodiment, the web comprises one or more engagement structures

along the length of the web for engagement of fencing wire.

[008] In an embodiment, the engagement structures comprise a plurality of spaced

apart apertures, the apertures being configured for receiving fencing wire there

through.

[009] In an embodiment, the flanges are substantially parallel to each other.

[010] In an embodiment, the elongate web lies in a plane that is substantially

perpendicular to the plane of at least one of the flanges.

[011] In an embodiment, the elongate web portion extending between the convergent

ends of the flanges comprises one or more cutting edges extending transversely

between end portions of the flanges.

[012] In an embodiment, the convergent ground engaging structure of the respective

flange comprises a triangular portion of the flange with tapering edges converging

towards an apex, the apex of the triangular portion being located at the end of the

respective flange.

[013] In an embodiment, the picket post further comprises: a first cutting edge

comprises: a first cutting surface that substantially lies in a first imaginary plane

defined by a first pair of parallel edges of the triangular portions of the respective

flanges; and a second cutting edge comprises a second cutting surface that

substantially lies in a second imaginary plane defined by a second pair of parallel

edges of the triangular portions of the respective flanges.

[014] In an embodiment, the flanges extend substantially along the entire length of

the elongate web between the two ends of the post.

[015] In an embodiment, thickness of the elongate web is equal to or less than

thickness of each of the flanges.

[016] In an embodiment, height of the elongate web is greater than width of one or

both flanges.

[017] In an embodiment, the flanges and the web are integrally formed.

[018] In an embodiment, the picket post is extruded from polymeric material.

[019] In an embodiment, the picket post is extruded from fire resistant polymeric

material.

BRIEF DESCRIPTION OF THE DRAWINGS

[020] Preferred features, embodiments and variations of the invention may be

discerned from the following Detailed Description which provides sufficient information

for those skilled in the art to perform the invention. The Detailed Description is not to

be regarded as limiting the scope of the preceding Summary of the Invention in any

way. The Detailed Description will make reference to a number of drawings as follows:

Figure 1 is a perspective view of a picket post 100 in accordance with an embodiment

of the present invention.

Figure 2 is an enlarged perspective view of the picket post 100 showing the second

end 102.

Figure 3 is another enlarged view of the ground engaging portion 107 of the picket

post 100.

Figure 4 is an enlarged view of the first end 101 of the picket post 100.

Figure 5 illustrates test results for example 1 of the picket post 100.

Figure 6 illustrates test results for example 2 of the picket post 100.

Figure 7 illustrates test results for a comparative example (prior art Y-shaped picket

post).

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[021] Figures 1 to 3 illustrate a picket 100 in accordancewith a preferred embodiment

of the present invention. The picket post 100 comprises an I-shaped profile and

extends between two ends ie a first end 101 and a second end 102. The picket post

100 is provided with a pair of parallel flanges 110 and 120 extending along the length

of the post 100 with an elongate web 140 extending transversely in between the

flanges 110 and 120. In the presently described embodiment, the elongate web 140

is substantially perpendicular to the flanges 110 and 120. However, in other

embodiments, the elongate web 140 may extend transversely and may be inclined at

an angle. Similarly, the flanges 110 and 120 may not necessarily be parallel to each

other in alternative embodiments.

[022] The picket post 100 also includes a ground engaging portion 107 at the second

end 102. The ground engaging portion comprises a convergent configuration which

allows the picket post 100 to be conveniently driven into soil. Specifically, each of the

flanges 110 and 120 of the post 100 terminates at the second end 102 to form a

convergent ground engaging structure 107. Referring to Figure 3, the convergent ground engaging structure 107 of each of the respective flanges 110 and 120 comprises a corresponding triangular portions 112 and 122. Each of the triangular portions 112 and 122 converges with their respective tapering edges 114 and 124 converging towards a respective apex. The apex for each flange 110 and 120 is located substantially at the second end 102 of each flange 110 and 120 as is evident in Figure 3.

[023] The elongate web 140 comprises two cutting edges that extend in between

triangular portions 112 and 122 of the spaced apart flanges 110 and 120. Specifically,

a first cutting edge 144 comprises a first cutting surface that substantially lies in a first

imaginary plane defined by a first pair of parallel edges 114 and 124 of the triangular

portions of the respective flanges. Whilst, figure 3 does not clearly illustrate a second

cutting edge, the second cutting edge comprises a second cutting surface that

substantially lies in a second imaginary plane defined by the second pair of parallel

edges of the triangular portions 112 and 122 of the respective flanges 110 and 120.

[024] Turning to the I-shaped profile of the picket post 100, it is important to note that

the flanges 110 and 120 in combination with the elongate web 140 extending there

between extending substantially along the entire length of the picket post 100 provide

substantially improved strength characteristics over the known picket posts such as

the "star picket" post. Without being bound by theory, the inventor hypothesizes that

the I-shaped profile allows the picket post 100 to undergo unidirectional bending

parallel to the web 140. The horizontal flanges 110 and 120 resist the bending

movement and the web 140 resists shear stress. As a result, it is expected that

installing the picket post 100 by ensuring that the major outer surface for each of the flanges 110 or 120 face towards and potential causes that can cause bending. By way of example, if the picket post 100 is positioned for fencing a cattle property, positioning the major outer surface of any one of the flanges 110 and 120 faces cattle such that any bending forces exerted by cattle is experienced by the flanges 110 or 120.

[025] Furthermore, the picket post 100 comprises engagement structures in the form

of apertures 105 are positioned along a central portion of the elongate web 140. During

use, strands of fencing wire can be passed through the apertures 105. The inventors

have found that provision of the engagement structures along the elongate web 140

reduces instances of failure of the picket post 100 at the aperture location thereby

addressing yet another problem in the art. When excessive forces are applied to the

picket post 100 (by livestock), a significant part of the force is exerted on the wide

flanges 110 or 120 of the I-shaped picket post 100. As a result, the elongate web 140

does not experience excessive bending forces as a result of which the picket post 100

is less susceptible to failure at the aperture location during such periods when bending

forces are being applied on the picket post 100. Figures 5 to 6 illustrate two examples

where bending resistance of the picket post 100 (with different dimensions for each of

examples 1 to 3) has been tested.

[026] For example 1 shown in Figure 5, the fence post 100 tested comprises flanges

110 and 120 that are 30mm wide with an elongate web 140 that is 65mm wide. The

yield strength 275 MPa may be readily increased by using polymeric material such as

fibreglass. Simulation studies for the fence post of example 1 were carried out by

exerting a force of 1 tonne on the upper section of the fence post 100. The extent of

bending is reduced significantly.

[027] For example 2, shown in Figure 6, the fence post 100 tested comprises flanges

110 and 120 that are 50mm wide with an elongate web 140 that is also 50mm wide.

In this example, the extent of bending for the fence post 100 was found to be reduced

sufficiently to hold back a cow pushing a load of1/4 tonne on the top portion of the

fence post 100. It can be seen in Figure 6 that the top portion of the fence post 100

can withstand stress of upto 949 MPa.

[028] In contrast, a comparative example has been shown in Figure 7 where by a

conventional Y-shaped picket made from stainless steel has been tested. it is evident

that the Y-shaped picket post is overloaded almost 16 times at the bending location

when the same amount of force (1/4 tonne-indicative of forces exerted by cattle) are

applied to the top portion of the y-shaped post.

[029] Whilst the method of manufacture for the picket post 100 is not limiting, it is

envisioned that the picket post 100 may be manufactured by extrusion. Moreover,

polymeric materials including fire resistant phenolic resins may be used in some

embodiments to provide a combination of improved strength and fire resistance to the

picket post 100.

[030] In compliance with the statute, the invention has been described in language

more or less specific to structural or methodical features. The term "comprises" and

its variations, such as "comprising" and "comprised of' is used throughout in an

inclusive sense and not to the exclusion of any additional features.

[031] It is to be understood that the invention is not limited to specific features shown

or described since the means herein described comprises preferred forms of putting

the invention into effect.

[032] The invention is, therefore, claimed in any of its forms or modifications within

the proper scope of the appended claims appropriately interpreted by those skilled in

the art.

Claims

1. A picket post comprising: an elongate web extending between two ends of the post; a pair of flanges extending along the length of the post with the elongate web being transversely positioned between said flanges; wherein each of said flanges at one end of the post terminates to form a respective convergent ground engaging structure to allow said one end of the post to be driven into the ground.

2. A picket post in accordance with claim 1 wherein the web comprises one or more engagement structures along the length of the web for engagement of fencing wire.

3. A picket post in accordance with claim 2 wherein the engagement structures comprise a plurality of spaced apart apertures, the apertures being configured for receiving fencing wire there-through.

4. A picket post in accordance with any one of the preceding claims wherein the flanges are substantially parallel to each other.

5. A picket post in accordance with any one of the preceding claims wherein the elongate web lies in a plane that is substantially perpendicular to the plane of at least one of the flanges.

6. A picket post in accordance with any one of the preceding claims wherein the elongate web portion extending between the convergent ends of the flanges comprises one or more cutting edges extending transversely between end portions of the flanges.

7. A picket post in accordance with any one of the preceding claims wherein the convergent ground engaging structure of the respective flange comprises a triangular portion of the flange with tapering edges converging towards an apex, the apex of the triangular portion being located at the end of the respective flange.

8. A picket post in accordance with claim 7 when dependent on claim 6 wherein a first cutting edge comprises:

a first cutting surface that substantially lies in a first imaginary plane defined by a first pair of parallel edges of the triangular portions of the respective flanges; and

a second cutting surface that substantially lies in a second imaginary plane defined by a second pair of parallel edges of the triangular portions of the respective flanges.

9. A picket post in accordance with any one of the preceding claims wherein the flanges extend substantially along the entire length of the elongate web between the two ends of the post.

10. A picket post in accordance with any one of the preceding claims wherein thickness of the elongate web is equal to or less than thickness of each of the flanges.

11. A picket post in accordance with any one of the preceding claims wherein height of the elongate web is greater than width of one or both flanges.

12. A picket post in accordance with any one of the preceding claims wherein the flanges and the web are integrally formed.

13. A picket post in accordance with any one of the preceding claims wherein the picket post is extruded from polymeric material.

14. A picket post in accordance with any one of the preceding claims wherein the picket post is extruded from fire resistant polymeric material.